How to Use a Coupler
A two-part device called a coupler lets you change decorating tips without changing the bag. The two parts of the coupler are the base and the ring.
Remove ring from coupler base. Drop the coupler base, narrow end first, into the bag and push it down as far as you can.
For Featherweight Bags: Using a pen or pencil, mark the spot on the outside where the bottom screw thread (closest to tip) is outlined against the bag material.
For Disposable Bags: Mark a spot on the outside that is 1/4 inch BELOW the bottom screw thread.
Push the coupler base up into the bag so that you can cut an opening at the mark.
Push the coupler base down through the opening. One thread should be showing. Place a decorating tip over the part of the base extending from the bag.
Put the ring over the tip and twist it on, locking the tip in place.